Study on Logging Gaps Regeneration in Secondary Broad-leaved Forest in Changbai Mountain

The regeneration trait of logging gaps in relation to sizes and ages in secondary broad-leaved forest which was predominated by Tilia amurensis,Acer mono and Quercus mongolica in Changbai Mountain was studied.The research result showed that there were 42.8%(canopy gaps area20 m2),23.8%(20～40 m2),33.4%(40～60 m2) in the proportion of gap size.38.1% of gaps shape were rotundity and 61.9% were oval.38.5% of the oval gaps lay in N-S direction,46.2% in W-E direction and 15.3% in N-E to S-W direction.These gaps were usually formed after 3～4 trees logged which were mainly composed of Tilia amurensis,Quercus mongolica and Maackia amurensis.The regeneration layer was dominated by the shrub in non-gap stands but arbor in the gaps.Moreover,the dominance would rise with increasing sizes and ages of gaps.The species diversity and density were obviously more in gaps than in non-gap stands.The synthesis diversity had a tendency to decline with increasing sizes and ages of gaps.The dominance species were different in gaps of different sizes,but were mainly composed of intolerant species.